Air pollution linked to lung cancer

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Long-term exposure to the tiny particles of soot and dust released in car fumes and by coal-fired power plants and factories significantly increases the risk of dying from lung cancer, according to a 16-year study carried out in the United States.

The findings — which have particular relevance in the developing world, as it contains the world’s most polluted cities — echo previous research showing that living in smoggy urban centres can increase the risk of heart attacks, strokes and asthma. But this is the first statistical evidence of a direct link with lung cancer.

“We found that the risk of dying from lung cancer as well as heart disease in the most polluted cities was comparable to the risk associated with nonsmokers being exposed to second-hand smoke over a long period of time,” says Arden Pope of Brigham Young University, one of the lead authors of the study.

The researchers, whose results are published in the 6 March issue of the Journal of the American Medical Association, examined the health records of 500,000 US citizens.

They also analysed data on the atmospheric concentration of particles smaller than 2.5 microns — a fraction of the thickness of a human hair — in the 100 cities where the participants lived.

The number of lung cancer deaths increased 8 per cent for every increase in particulate matter of 10 micrograms per cubic metre of air.

“This is a most worrying issue,” says Anumita Roychowdury, coordinator of air pollution control at the Centre for Science and Environment in Delhi, India.

Levels of particulate pollution in Indian cities can reach 900 micrograms per cubic metre, she says — nine times India’s permissible level. By comparison, the US Environmental Protection Agency’s limit is 15 microgram per cubic metre.

She adds: “These are really critical and dangerous levels of pollution. We need to design strategies to make a quantum leap and bring down levels immediately and drastically.”